Y. A. Tillayev, A. M. Azimov, A. R. Hafizov
Astronomical seeing measurements were carried out at Maidanak observatory during the period from August to November 2018 using DIMM (Differential Image Motion Monitor). The median value of seeing for the entire period was determined as 0.54 arcseconds. This value was compared to the seeing data of the period 1996-2002.
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Results of 2005-2007 campaign of measurement of the optical turbulence vertical distribution above Mt. Maidanak are presented. Measurements are performed with the MASS (Multi-Aperture Scintillation Sensor) device which is widely used in similar studies during last years at several observatories across the world. The data analysis shows that median seeing in free atmosphere (at altitudes above 0.5km) is 0.46 arcsec and median isoplanatic angle is 2.47 arcsec. Given a rather long atmospheric coherence time (about 7 ms when the seeing is good) such conditions are favorable for adaptive optics and…
The Shack-Hartman wavefront sensor designed for final acceptance of 2.5m SAI telescope allows to measure the shape of the wavefront on exit pupil of the telescope using a bright star. The reference laser source on wavelength 532 nm is used for measurements. During testing the device at different telescopes it was found out what it's probable to estimate some properties of air streams in the dome. Such estimations have been made for three domes: 1.5 m AZT-22 and 1.0 m Zeiss telescope of Maidanak Observatory, Uzbekistan and for 2.6 m telescope ZTSh of Crimean observatory, Ukraine. The following …
We report results of a two-year campaign of measurements, during arctic winter darkness, of optical turbulence in the atmospheric boundary-layer above the Polar Environment Atmospheric Laboratory in northern Ellesmere Island (latitude +80 deg N). The data reveal that the ground-layer turbulence in the Arctic is often quite weak, even at the comparatively-low 610 m altitude of this site. The median and 25th percentile ground-layer seeing, at a height of 20 m, are found to be 0.57 and 0.25 arcsec, respectively. When combined with a free-atmosphere component of 0.30 arcsec, the median and 25th pe…
We present for the first time a new method to estimate the seeing using remote sounding from the IR night time data of the GOES 12 satellite. We discuss the derived correlation between the ground data and the satellite derived values from the analysis of the sites located at Cerro Paranal (Chile) and Roque de los Muchachos (Canary Islands, Spain). We get a ground-satellite correlation percentage of about 90%. Finally, studying the correlation between the afternoon data and the following night, we are able to provide a forecast of the photometric night quality.
Seeing, the angular size of stellar images blurred by atmospheric turbulence, is a critical parameter used to assess the quality of astronomical sites. Median values at the best mid-latitude sites are generally in the range of 0.6--0.8\,arcsec. Sites on the Antarctic plateau are characterized by comparatively-weak turbulence in the free-atmosphere above a strong but thin boundary layer. The median seeing at Dome C is estimated to be 0.23--0.36 arcsec above a boundary layer that has a typical height of 30\,m. At Dome A and F, the only previous seeing measurements were made during daytime. Here …
Atmospheric turbulence is the one of the major limiting factors for ground-based astronomical observations. In this paper, the problem of short-term forecasting seeing is discussed. The real data that were obtained by atmospheric optical turbulence (OT) measurements above Mount Shatdzhatmaz in 2007--2013 have been analysed. Linear auto-regressive integrated moving average (ARIMA) models are used for the forecasting. A new procedure for forecasting the image characteristics of direct astronomical observations (central image intensity, full width at half maximum, radius encircling 80% of the ene…
To explore the issue of performing a non-interactive numerical weather forecast with an operational global model in assist of astronomical observing, we use the Xu-Randall cloud scheme and the Trinquet-Vernin AXP seeing model with the global numerical output from the Global Forecast System to generate 3-72h forecasts for cloud coverage and atmospheric seeing, and compare them with sequence observations from 9 sites from different regions of the world with different climatic background in the period of January 2008 to December 2009. The evaluation shows that the proportion of prefect forecast o…
Directly Characterizing Dome Seeing: Differential Image Motion Sensor Using Multisources (DIMSUM)
针对天文观测中圆顶视宁度导致的图像退化问题，提出安装简便的DIMSUM装置，通过频闪成像测量差分图像运动直接表征局部折射率变化，在鲁宾天文台辅助望远镜的测试验证了其应用潜力。
Radio Frequency Interference (RFI) corrupts astronomical measurements, thus affecting the performance of radio telescopes. To address this problem, supervised segmentation models have been proposed as candidate solutions to RFI detection. However, the unavailability of large labelled datasets, due to the prohibitive cost of annotating, makes these solutions unusable. To solve these shortcomings, we focus on the inverse problem; training models on only uncontaminated emissions thereby learning to discriminate RFI from all known astronomical signals and system noise. We use Nearest-Latent-Neighb…
Atmospheric turbulence profiling with the Multistar Turbulence Monitor
本文提出利用多星湍流监视器分析大气湍流剖面，结合理论分析、仪器性能评估、数值模拟和实际观测，验证了该方法在湍流剖面和视宁度监测中的有效性。
The location of an astronomical observatory is a key factor that affects its scientific productivity. The best astronomical sites are generally those found at high altitudes. Several such sites in western China and the Tibetan plateau are presently under development for astronomy. One of these is Ali, which at over 5000 m is one of the highest astronomical sites in the world. In order to further investigate the astronomical potential of Ali, we have installed a lunar scintillometer, for the primary purpose of profiling atmospheric turbulence. This paper describes the instrument and technique, …
Seeing at Timau National Observatory Based on ERA5 Dataset
本文利用ERA5数据集分析Timau天文台的长期大气数据，评估其视宁度条件，发现视宁度中位数为0.79角秒，为天文台规划提供重要参考。
Xinglong Observatory of the National Astronomical Observatories, Chinese Academy of Sciences (NAOC), is one of the major optical observatories in China, which hosts nine optical telescopes including the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the 2.16 m reflector. Scientific research from these telescopes is focused on stars, galaxies, and exoplanets using multicolor photometry and spectroscopic observations. Therefore, it is important to provide the observing conditions of the site, in detail, to the astronomers for an efficient use of these facilities. In this …
Assessment of the AlUla Manara astronomical site in Saudi Arabia using ECMWF ERA5 Reanalysis data
本研究利用ERA5再分析数据评估AlUla Manara台址，发现其视宁度中位数1.5角秒、冷季PWV 3.2毫米、晴空率超79%，虽湍流条件略逊于其他候选地，但符合区域发展目标，故仍具竞争力。
Deconvolution for Large Astronomical Surveys: A Study of the Scaled Gradient Projection Method on Zwicky Transient Facility Data
本研究将SGP算法应用于Zwicky Transient Facility图像的单波段反卷积，发现该方法在保持测光流量、提高探测完整度及暗弱源揭示方面优于Richardson-Lucy反卷积且速度快八倍，有望集成至巡天流水线。
We installed two sets of Astronomical Site Monitoring System(ASMS) at Lijiang Observatory(GMG), for the running of the 2.4-meter Lijiang optical telescope(LJT) and the 1.6-meter Multi-channel Photometric Survey Telescope (Mephisto). The Mephistro is under construction. ASMS has been running on robotic mode since 2017. The core instruments: Cloud Sensor, All-Sky Camera and Autonomous-DIMM that are developed by our group, together with the commercial Meteorological Station and Sky Quality Meter, are combined into the astronomical optical site monitoring system. The new Cloud Sensor's Cloud-Clear…
We present results from the first year of a campaign to characterize and monitor the optical turbulence profile at the SAAO Sutherland observing station in South Africa. A MASS-DIMM (MultiAperture Scintillation Sensor - Differential Image Motion Monitor) was commissioned in March 2010 to provide continuous monitoring of the seeing conditions. Over the first month of the campaign, a SLODAR (SLOpe Detection And Ranging) from Durham University was also installed allowing an independent verification of the performance of the MASS-DIMM device. After the first year of data collection, the overall me…
Atmospheric optical turbulence seriously limits the performance of high angular resolution instruments. An 8-night campaign of measurements was carried out at the LAMOST site in 2011, to characterize the optical turbulence. Two instruments were set up during the campaign: a Differential Image Motion Monitor (DIMM) used to measure the total atmospheric seeing, and a Single Star Scidar (SSS) to measure the vertical profiles of the turbulence C_n^2(h) and the horizontal wind velocity V(h). The optical turbulence parameters are also calculated with the Weather Research and Forecasting (WRF) model …
Seeing Black Holes : from the Computer to the Telescope
本文回顾了从作者四十年前首批黑洞数值模拟到事件视界望远镜即将于2018年获得银河系中心超大质量黑洞首张图像的研究历程，展现了数值模拟对黑洞成像的奠基性贡献。
We present the first results of the site testing performed at Mt.~Shatdzhatmaz at Northern Caucasus, where the new Sternberg astronomical institute 2.5-m telescope will be installed. An automatic site monitor instrumentation and functionality are described together with the methods of measurement of the basic astroclimate and weather parameters. The clear night sky time derived on the basis of 2006 -- 2009 data amounts to 1340 hours per year. Principle attention is given to the measurement of the optical turbulence altitude distribution which is the most important characteristic affecting opti…
Pathway to Devasthal Astronomical Observatory, ARIES
本文记录了 ARIES 历时约 5 年在喜马拉雅地区建立 Devasthal 天文台的过程，介绍了其选址、三台光学望远镜的安装及与 TIFR 的合作，并概述了主要科学成果。
A seeing measurement device for the PoET solar telescope
本文介绍用于PoET太阳望远镜的视宁度测量装置，通过利用太阳作为扩展光源，实现白天视宁度测量，以优化观测 aperture 并确保科学性能。
Impact of Satellite Constellations on Observations with the 80-cm Telescope and the Mini-SiTian at the Xinglong Observatory, NAOC
本研究通过结合世界宽视场望远镜模拟数据与2019年和2023年的观测数据，分析了低地球轨道 mega-constellations 对80厘米望远镜和Mini-SiTian观测的影响，发现卫星轨迹干扰随部署增加而增加，特别是在夏季，且对弱源和靠近轨迹的天体影响更显著。
UBVRI night sky brightness at Kottamia Astronomical Observatory
本研究利用全自动光电光度计，首次在埃及Kottamia天文台通过UBVRI系统开展夜天亮度观测，测得各波段天顶亮度与色指数，分析了大气消光等特性，明确了周边新建城市对天光的影响。
The \oarpaf telescope is an $80\rm cm$-diameter optical telescope installed in the Antola Mount Regional Reserve, in Northern Italy. This work presents the results of the characterization of the site, as well as developments and interventions that have been implemented, with the goal of exploiting the facility for scientific and educational purposes. During the characterization of the site, an average background brightness of $22.40 \, m_{AB}$ ($B$ filter) -- $21.14 \, m_{AB}$ ($I$) per arcsecond squared, and a $1.5$--$3.0"$ seeing, have been measured. An estimate of the magnitude zero points …
There are many ways to solve the challenging problem of making a high performance robotic observatory from scratch. The Observatorio Astrofísico de Javalambre (OAJ) is a new astronomical facility located at the Sierra de Javalambre (Teruel, Spain) whose primary role will be to conduct all-sky astronomical surveys. The OAJ control system has been designed under a global point of view including not only astronomical subsystems but also infrastructure and other facilities. Three main factors have been considered in the design of a global control system for the robotic OAJ: quality, reliability an…
Sites for next-generation telescopes are chosen decades before the first light of a telescope. Site selection is usually based on recent measurements over a period that is too short to account for long-term changes in observing conditions such as those arising from anthropogenic climate change. In this study, we analyse trends in astronomical observing conditions for eight sites. Most sites either already host telescopes that provide in situ measurements of weather parameters or are candidates for hosting next-generation telescopes. For a fine representation of orography, we use the highest re…
At Paranal Observatory, the least predictable parameter affecting the short-term scheduling of astronomical observations is the optical turbulence, especially the seeing, coherence time and ground layer fraction. These are critical variables driving the performance of the instruments of the Very Large Telescope (VLT), especially those fed with adaptive optics systems. Currently, the night astronomer does not have a predictive tool to support him/her in decision-making at night. As most service-mode observations at the VLT last less than two hours, it is critical to be able to predict what will…
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